Final answer:
The molarity of potassium ions in a 0.122 M K₂CrO₄ solution is 0.244 M.
Step-by-step explanation:
To find the molarity of potassium ions in the solution, we need to consider the stoichiometry of the compound. K₂CrO₄ is composed of two potassium ions (K⁺) and one chromate ion (CrO₄²⁻). Therefore, for every one mole of K₂CrO₄, there are two moles of K⁺ ions.
Given that the molarity of the K₂CrO₄ solution is 0.122 M, the molarity of the potassium ions is two times that value, resulting in a final molarity of 0.244 M.
Therefore, the correct answer is c. 0.244 M.